Choke fitting



Patented Jan. 22, '1946 UNITEDTSTATES PATENT OFFICE V H V t I I I 2,393,423 1 Z v CHOKE FITTING Charles J. S'ehera, Turtle C'reekfla assignor to' The Westinghouse Air Brake Company, Wilmerdingj Pa a corporation or Pennsylvania I Application June 24, 1944, Serial No. 542,023 7 4 Cl'aims. (:QL1138-41) f This invention relates to a choke fitting of the type-to be used in afluid conducting passage of afluidpressure control apparatus.

Anobject of this invention is to providean improved-choke plug (i-r fitting arranged for use in a fluid conducting passage and ;having intimately associated therewith novel: fluid straining or; cleanin means which operates to remove forpassage immediately before the fluid; reaches the choked port in the plug. j

v A .further object, 'ofthe' invention is to provide an improvedchoke plug of the above type in which, a fibrous :fluidstraining, means isemployedthat has alarge surface area exposed to fluid. to be cleaned in orderto prevent clogging of the fluidstraining means and resultant .re-

. eign matter from the fluid flowing through the supplied from the brake pipe to the valve chamber 5 in amanner to be described more fully later. In its retarded rechaigedposition the piston clears a passage It so that chamber 4 connects with said passage H which is open. at itsv other end to a chamber l2 formed in the body and closed at the top .by a screw plug. [3 in a manneridentical with that of chamber l. Located between the chamber I 0 and the chamber l2,fandbe-- tweenchamber l0 and chamber 1, are identical choke plugs l4 and [5, respectively,- which have screw-threaded connection with the body or casing I .andwhichare'providedfor the purpose. of controlling. the flow offluid under pressure'from the brake pipe to valve chamber 5, the left-hand V plug llbeing shown in section. for purposes of striction of the flow ofQfiuid therethroughto the choked portion in the plug by matter separatedfrom the fluid. v v

Another object is to-provide an improved choke plug of the type described in the preceding paragraph having means whereby the fibrous .fiuid cleansing material. isv so supported that it will be, maintained spaced away from the choke port collected foreign a; sufiicientdistance that it will not restrict the flow. of fluid through the port in the chokeplugl A further object is to provide a choke plug- 7 having a simple but very effective mean .for mounting and removably securing the straining element thereto,- 3

,Other objects of the ;-invention and features of novelty will be apparent from the following de-' scription" taken in connection withthe accompanying drawing, in-which Fig; .1 is .anenlarg'ed fragmentary. diagrammatic vview, pa1'-tly in section, .ofan improved brake controlling valve de vice..,'erfnbedying the invention and 1i'ig...2'..is a stilliurther enlarged. fragmentary sectional-view of a portion of the choke fitting. h Referring to the drawing, there is illustrated therein a (fragment ofthe. serviceportion of ,a brake controlling valve device of the type. shown and describedinU. .8. Patent, No'. 2,031,213, issued February "18, 1936; toC. C. Farmer. The service portion'comprises a body I-. having. a bore'2 there; in in which is mounted a piston 3 having at one interposed therein. Piston 3 has at. its otherface a valve chamber 5 which is constantly connected byway of a passagelfi with a chamber. 1 iormed in the body I and closed at the top by a screw plug, 8.

.The piston 31in its iull'release and charging position in the bore? o nscommunication from the chamber 4 to a port and passage 9 which communicates with aconductor chamber In in the body l'through which'fluid under pressure is illustrating the details of construction of the-fitting as-a whole. 7 I

It will be observed that with the piston '3 -in full release and charging positionas shown; both passage 6 and passage H are connected to chamher .5 and therefore fluid under pressurev will flow from chamber 4 to chamber H) by .way of port and passage 9, and thenceto chamber 5 by way of choke plug l4,. chamber [2 and port and passage ll, and also byway of. chokeplug l5, chamber '1. andpassage .6. With the piston 3 in retarded recharged position, i. e.,. in its extreme right-hand position, in which the rear face of the piston engages a stop lug la carried by thebody .l, port and passage l lwill be connected to'chamberl as is port and passage '9 and consequently there will be no flow of fluid under pressure through choke plug IL, .Since passage Bis still connected tojchamber 5, choke plug IE will control the flow of fluid under pressure from brake pipe'to chamber 5. As both choke plugs are of the same now area, the flow. capacity is only half that when both choke. plugs are used.

' As shown in the illustrationin sectionof choke plug l4, the choke plug comprises'a body it which may be formed of any suitable material such as brass. Formed-in thetop portion, oithe body "[6 viewed inthe drawing is. an, annular recessv l1 having in itslwall a plurality of splines l8 ,for. engagement by a spline wrench.

exterior peripheral surface of this portion of the bodyifi isprovide d with tapered threads 19 for engaging corresponding threads Zll formed-in the wall between the chamber In and the chamber. I2. The. lower end oi the body terminates in an annularstud portionzl. I

'Ihe stud portion 2! is provided with a bore 2 2 which is coaxial withthe'body'li and is open to the 'recess' I! by way of an axial restricted port or passage 23,. This bore 22 is also open by wayof. a plurality of transverse apertures or perforations ,24 toa plurality of annular grooves 25 provided in. the periphery of the stud portion 2|, the apertures and grooves being so arranged in relation to each other that each is connected to more than one of the other. As shown in detail in Fig. 2 this is accomplished by having the perforations pass through the partitions which define the grooves 25 and by making the perforations of greater diameter than the width of such partitions.

Associated with the body I6 is a fluid straining element 25 which may be formed of any suitable material, but preferably of a compacted fibrous material such as a felt, in the form of a cup shaped body having an outside diameter slightly smaller than that of the threaded portion of the body It and an inside diameter slightlylarger than that of the stud portion 2i. This felt body may be placed over the stud portion 2| so as to snugly engage the bottom surface of the threaded portion and completely overlay or enshroud the stud portion of the body l6. For maintaining the straining element 26 securely mounted on the stud portion 2| there is provided a resilient retaining element 21 wound in the form of a helix which has been expanded and passed over the straining element so as to be positioned a short distance from its upper end as viewed in the drawing. When released, the constricting pressure of the retaining element 21 squeezes the straining element into groove 25 at thebase or upper end of the stud portion and will hold it in such position. I

It should be understood that the straining element does not engage the surfaces of any of the grooves 25 except that of the uppermost groove just described. It should be noted that by reason of the retaining element being spaced away from the surfaces of the grooves there are provided an-. nular unoccupied channels between the straining element and the apertures or perforations 24 in the stud portion, thereby obtaining the maximum filtering surface and reducing the possibility of the clogging of apertures 24. Also, since each channel is connected to more than one aperture and each aperture is connected to more than one channel, should one connection between channel and aperture by chance become clogged, the clogged connection will be by-passed by routes through other connections thus insuring the free flow of fluid through the fitting.

In the service for which this invention is intended, the flow offluid to the passage in which the strainer is mounted is normally in one direction only, and therefore, as shown in the drawing the strainer is arranged so that when fluid flows. through the port and pass-age 9 to the chamber [0, it will then flow through the airstraining element 26 before reaching the restricted passage 23 which is to be protected. If the fluid supplied to the chamber It! contains any foreign matter, it will be removed by the straining element 26 before reaching the restricted passage 23 in the choke plug M where it might partially or completely close the passage, thereby interfering with the intended operation of the valve device. Thus the flow of fluid to the choke plugs is through the straining element 26 into thebody l6 of the choke plug, and therefore, there will be no tendency of, dislodgment of this element by this flow of fluid, the tendency of such flow being to seat the element more firmly n the stud portion 2!.

It will here be noted that substantially the entire outer surface. of the straining element 26 is exposed to the chamber l0 and consequently to the fluid supplied thereto, thus providing a carried by said body portion, an axially disposed fluid conducting passage in said body and stud portions, said stud portion having a plurality of grooves formed on the exterior thereof, a partition between said grooves, a radially disposed passage extending through said partition and communicating with said axially disposed passage, said radially disposed passage being of greater diameter than the width of said partition to establish communication between said grooves, and a filter element encircling said stud portion, said partition supporting said element out of engagement with the bottoms of said grooves and thereby providing an unoccupied fluid conducting space between said grooves and said radially disposed passage.

2. A choke fitting for a fluid conductor, comprising a body portion having a bore of small flow area therethrough, a stud portion carried by said body portion and having a boretherein in communication with the first mentioned bore and of greater flow area than the first mentioned bore, a plurality of grooves formed on the exterior of said stud portion, a partition between said grooves, and a passage extending through said partition from the exterior of said stud to the second mentioned bore, said passage being of greater diameter than the width of said partition, and a fllter element enshrouding said stud portion, said partition maintaining said filter element spaced from the bottoms of said grooves.

3. A choke fitting for use in a fluid conductor for controlling the rateQof flow of fluid through the conductor and cleaning thefluid flowing through the conductor, said choke fitting com-. prising a body portion having therein a flow refstricting passage and comprising a perforated stud portion through which fluid flows to said passage, a fluid straining element mounted on and covering said stud portion through which straining element fluid flows to said passage, and a resilient constricting member for removably main-, taining the straining element on said stud portion, said stud portion havingat itsbase an an.- nulargroove into which a portion of said straining element is squeezed by said retaining member. 1

4. A choke fltting to be, interposed in a .fluid conductor through which fluid under pressure normally flows in one direction only, said fltting comprising a body portion arranged. at its periphery for mounting engagement with the wall of said conductor and having a passage .of small flow area therethrough for restricting the flow of fluid through said conductor, a stud portion 7 provided with a plurality of perforations which CHARLES J. SEKERA. 

